The invention relates to a control device for imposing a programme of speeds of relative displacement between a workpiece and a tool. Although the invention is applicable to workpieces of any form it is particularly applicable to workpieces in the form of plates. The invention is designed particularly to apply to workpieces made of glass or plastics material, for example lenses or glass panes or plate glass and in particular to the window panes of car windows.
The increase in production rates which are desired makes it necessary to reduce the time of work on each piece and consequently to increase the speed of relative displacement between the tool and the workpiece. Under these conditions it is obviously not possible to use a speed of displacement which is both rapid and uniform since for example the cutting of a very round piece of glass plate can only be carried out slowly while the cutting of a straight or only slightly curved piece can be carried out at a high speed. It is therefore necessary to provide devices by means of which the instantaneous speed of relative displacement between the tool and the workpiece can be varied according to the contour along which the tool is required to work on the workpiece.
The apparatus according to the invention precisely enables the instantaneous speed of relative displacement between a workpiece and its tool to be varied according to a predetermined programme which can be suitably adapted to each type of work to be carried out.
The apparatus according to the invention is designed to be used in association with a machine which comprises a tool in relative displacement against the workpiece on which it is required to operate, the function of the apparatus being to impose a programme of speeds on this displacement.